Definition and classification of mental retardation: a reply to Zigler, Balla, and Hodapp.

Zigler, Balla, and Hodapp (1984) have proposed that mental retardation be defined as an IQ at least 2 standard deviations below the mean and classified as having organic or genetic etiology. These proposals are found to be based upon questionable assumptions about mental retardation. An alternative conceptual framework for definition of mental retardation is proposed and used to evaluate the merits of IQ and social competence in determining mental retardation. The use of IQ alone is judged to be inappropriate and potentially harmful when applied to individuals and when used to formulate public policy. Other researchers have established that there is insufficient evidence to attribute genetic or organic etiology to most mental retardation.